Glossary of terms, abbreviations and conversions

Terms
THE FIRST SECTION OF THIS GLOSSARY defines unfamiliar terms used in this manual. The definitions are intended to make the terms understandable to the novice rather than to the biologist.

Abdomen: commonly referred to as the ‘tail’ of prawns, this is the area con taining segments from which the swimming appendages origi
nate. See Table 1 of the main text for details.
Agonistic: fighting, combative behaviour.
Artemia: scientific name for brine shrimp.
Bacteria: microscopic single-cell organisms of a kind which can cause dis ease.
Bank: the elevated rim of a pond. Also called embankment, dyke (dike), berm or bund.
Batch culture: a system of rearing prawns involving the total harvest, by seining or draining or both, at a certain interval after stocking (see
Box 15). The ponds are then drained before re-stocking.
Benthic: organisms living on the bottom of the pond; opposite of planktonic. Berm: see Bank.
Berried: egg carrying.
Brine shrimp: a small crustacean whose larvae are used to feed larval prawns.
Brood chamber: an area formed beneath the abdomen of the mature female by the expansion of the pleura, in which the fertilized eggs are carried
before hatching. In this area the eggs are oxygenated by move
ment of the pleopods.

 

BSE: bovine spongiform encephalopathy, a serious disease of rumi nants, which seems to be associated with the incidence of a simi
lar disease in humans. Colloquially known as mad cow disease.
Buffer: a substance or substances which resist or counteract changes in the acidity or alkalinity of water.
Bund: see Bank.
Carapace: a dorsal cover which obscures the division between the true head (cephalon) and the thorax (jointly known as the cephalothorax) of prawns.
Caridean: a crustacean which belongs to one of the two main groups (infra orders; sections) which form the suborder Natantia of the order
Decapoda. The group is called the Caridea; thus these crus taceans are known as carideans. Within this infraorder (Caridea) the family of main importance to aquaculture is the
Palaemonidae, which, in addition to containing some marine prawns (e.g. Palaemon serratus), contains most of the commonly farmed freshwater prawns belonging to the genus
Macrobrachium (e.g. Macrobrachium amazonicum, M. malcolm sonii, M. nipponense and M. rosenbergii).
Cephalon: part of the area under the carapace. Contains the segments from which the eyes, antennae, and three other pairs of appendages originate. See Table 1 of the main text for details.
Chela: claw
Chelae: plural of chela.
Chelating: the action of a chelator.
Chelator: a substance which binds ions and holds them longer in suspen sion, thus (for example) making nutrients available to algae longer. Chelators also sequester (bind) heavy metals that may have entered the system from exterior sources, thus reducing the toxicity that they may have for prawn larvae. In greenwater sys tems both chelating actions would be valuable; in clearwater sys tems, it is the reduction of toxicity that is the most likely to cause the beneficial effect.
Cheliped: literally a leg with a claw on it. Strictly, all the pereiopods have claws on them and are therefore chelipeds. However, only on the first two pairs are the claws (chelae) formed into pincers. In prac tice, the word cheliped is often only applied to the legs with the largest pincers (in freshwater prawns these are the longest legs, the second pereiopods).
Clearwater: larval rearing water which does not contain green planktonic algae.
Combined system an intermediate form of culture between batch and continuous of culture: culture, on which the grow-out and harvesting sections of this manual are based (see Box 15).
Continuous culture: a system of rearing prawns in ponds which involves continuous pond operation (see Box 15). Ponds are not regularly drained for harvesting, nor completely harvested. The larger animals are reg ularly removed by seine net for marketing, leaving the smaller ones to grow on. The ponds are regularly restocked with postlar vae or juveniles.

Count: this term, used by shrimp buyers, refers to the number of prawns or prawn tails per unit weight. When using this term, it is impor tant to state whether shell-on/head-on, shell-on tails or peeled tails are being described.
Crustacea: group of animals including shrimp and prawns, lobsters, and crabs.
Decapsulation: the removal of the hard outer layer (shell) of Artemia cysts. Dike: see Bank.
DO2: dissolved oxygen content (of water). Sometimes reported as ppm and sometimes as percent of saturation level. In this manual, ppm has been used.
Dorsal: upper.
Dyke: see Bank. .
Endopod: anatomical term referring to the inner part of the end of an appendage.
Epilimnion: upper layer of water in a stratified lake or reservoir.
Exopod: anatomical term referring to the outer part of the end of an appendage.
Exoskeleton: the outer hard coat of crustaceans, often referred to as the shell. Exuvia: the cast shell (exoskeleton) after moulting.
Feed Conversion the amount of food necessary to produce one unit weight (wet) of Efficiency (FCE): prawns. For example, if a pond produces 1 250 kg of prawns and 3 200 kg of food were used during the rearing period, the feed
conversion efficiency is: FCE = 3 200 ? 1 250 = 2.56. It follows, therefore, that the lower the FCE is, the better the efficiency (of conversion into final product) of the food is. The FCE of wet feeds will be much higher than that of dry feeds because of the differ ence in moisture content. To directly compare two feeds with dif ferent moisture contents, it is necessary to convert the different feed conversion efficiencies to a standard moisture content or to bring the relative cost of the feeds into consideration. The latter option is more meaningful. For example, let us suppose that Feed A has an FCE of 2.8 and a cost of US$ 492/mt. On the other hand, Feed B has an FCE of 6.9 and a cost of US$ 215/mt. Which is the ‘better’ feed from the farmers’ point of view? To produce one ton of prawn using Feed A would cost US$ 492 x 2.8 = US$ 1 377.60; using Feed B it would cost US$ 215 x 6.9 = US$ 1 483.50. Feed A is therefore cheaper to use, even though its unit price is more than twice than that of Feed B.
Feed Conversion this is the same as feed conversion efficiency, except that it is Ratio: written as a ratio (FCR), i.e. a feed conversion efficiency of 2.8 is written as a feed conversion ratio of 2.8:1. This means 2.8 kg of food is necessary to produce 1 kg of prawns live weight. The two terms are frequently used synonymously. For example, you may often see an expression such as ‘the FCE of the diet was 2.8:1’.
Genital pores: the openings of the reproductive organs to the exterior of the ani mal. In males they are between the fifth pair of pereiopods and in females between the third pair of pereiopods.
Gill chamber: the area at the sides of the ‘head’ of the prawn that contains the gills through which the prawn takes oxygen from the water and releases carbon dioxide during respiration.
Greenwater: larval rearing water with an induced density of green planktonic algae.
Head: a common term that includes both the true head (cephalon) and the thorax area, which are below the carapace.
Heterogeneous: different; diverse.
HIG: heterogeneous individual growth.
H2S: hydrogen sulphide.
Juvenile: this is a very indefinite term and could be used to refer to any prawn that is no longer a larva but is not yet sexually mature.
However, in farming, this term is usually used to refer to animals which are larger (older) than PL when used for stocking grow-out ponds (or open waters), that is prawns up to about 3 g in weight.
The main text of the manual contains details of the rearing of PL to juvenile sizes in nursery facilities. In their natural habitat, freshwater prawns at this stage can move against strong cur
rents, climb rapids, and move across wet areas to other waters.
They are very hardy by this time.
Lab-lab: a term which originated in the Philippines, that refers to the complex of blue-green algae, diatoms, bacteria and various ani
mals that forms on the bottom or other surfaces of ponds and tanks.
Larva: singular of larvae.
Larvae: animals that have hatched from eggs but have not yet metamor phosed into postlarvae. They require brackishwater and swim
upside down, tail up and backwards. Their anatomy (form) is also different from juveniles or adults.
Metamorphosis: the process of transformation by which a larva becomes a post larva and takes on the miniature appearance and the behaviour of an adult.
Moult: to cast the shell.
Orbit: eye socket.
Ovigerous: having ripe ovaries.
Penaeid: a crustacean which belongs to one of the two main groups (infra orders; sections) which form the suborder Natantia of the order
Decapoda. This group is called the Penaeidea; thus these crus taceans are commonly known as penaeids. Within this infraorder (Penaeidea) the family Penaeidae contains most of the commonly farmed marine shrimp (e.g. Litopenaeus (Penaeus) vannamei, L. stylirostris, Penaeus monodon, P. semisulcatus, Fenneropenaeus merguiensis, F. chinensis, Marsupenaeus japonicus, Farfante penaeus aztecus and Metapenaeus spp.).
Pereiopods: an anatomical term, referring to the five pairs of legs below the thorax. The first two pairs are used for catching food, in mating,
and in agonistic behaviour; the last three pairs are ‘walking legs’.
PL: an abbreviation for postlarva, postlarvae
Planktonic: living organisms (mainly microscopic) that are found within the body of the water (in other words, the opposite of benthic).
Pleopods: an anatomical term, referring to the five pairs of legs below the abdomen (sometimes called the ‘tail’, when prawns are headed before sale) of the prawn, which are used mainly for swimming (swimmerets).
Pleura: an anatomical term, referring to the sides of the abdominal seg ments.
Postlarva: singular of postlarvae (PL).
Postlarvae: a term (PL) usually applied to animals from immediately after metamorphosis from the larval stage up to about 10-20 days later.
This term and the word ‘juvenile’ are applied very loosely and sometimes synonymously. Postlarval freshwater prawns swim and behave like adult prawns and, as they age, cling to or crawl on surfaces rather than swim freely in the body of the water.
ppm: parts per million. A unit of chemical measurement used for report ing the levels of trace materials (e.g. oxygen dissolved in water) or of an additive (e.g. active chlorine). It is equivalent to 1 ml/m3, 1 g/mt, or 1 mg/litre, for example. Where this manual prescribes the addition of a substance at a certain level, the actual amount to add can be calculated as follows. Say that you are recommended pro vide 50 ppm of substance X in a container (e.g. a tank). Let us sup pose that the volume of water in the tank that you want to dose is 250 L. The expression 50 ppm (parts per million) means 50 parts of substance X to every 1 million parts of water (e.g. 50 ml of sub stance X in 1 million ml of water). As 250 L = 250 000 ml, the amount of substance X (which may be measured in ml or g) to add is: 50 x 250 000 ? 1 million = 12.5 ml (or g).
ppt: parts per thousand. A unit of measurement usually applied to salinity. Also written in other documents as ‰. The salinity of full seawater varies but is often around 35 ppt (35‰). The water in freshwater prawn (Macrobrachium rosenbergii) larval rearing tanks is kept at 12 ppt (12‰).
Prophylactic: a medicine or course of action which tends to prevent disease. Protozoa: a microscopic (usually single-celled) animal.
Puddling: breaking the structure of the soil before the pond is filled. This is achieved by saturating the soil at the bottom of the pond; allow ing the water to soak into the soil; and hoeing or ploughing it. The amount of water necessary to saturate the soil is roughly 200-300 mm (2 000-3 000 m3/ha).
Rostrum: anatomical term, referring to the sharp ‘beak’ which extends from the head of prawns.
Salinity: see ppt.
Sequester: bind (see chelator).
Sessile: not on stalks (applies to larval eyes in the first larval stage).
Substrate: something which provides extra shelter in a tank or pond, such as nylon screens or nets, pipes, branches, etc.
Supernatant: the clear liquid after a precipitate has settled.
Swimmerets: synonym for pleopods.
Tail: a common term referring to the abdomen, or rear part of prawns.
Telson: anatomical term, referring to the pointed central projection of the last abdominal segment of prawns. The telson and the uropods together form the ‘tail fan’ of prawns (and other crustacea).
Thorax: part of the area under the carapace. Contains the segments from which eight appendages originate. See Table 1 of the main text for details.
Uropod: anatomical term, referring to two rigid structures that appear on the final abdominal segment at the sides of the telson.
Ventral: lower.
Walking legs: synonym for the 3rd, 4th and 5th pereiopods.
Abbreviations
NOT ALL OF THE FOLLOWING abbreviations have been used in this manual. However, they are provided to help you when you read other documents.
< less than
> greater than
n.a. not analysed or not available
µm micron
mm millimetre
cm centimetre
m metre
km kilometre
inch inch
ft foot
yd yard
mi mile
ft2 square foot
yd2 square yard
mi2 square mile
m2 square metre
ha hectare
km2 square kilometre
cc cubic centimetre (= ml)
m3 cubic metre
ft3 cubic foot
yd3 cubic yard
µl microlitre
ml millilitre (= cc)
L litre
µg microgram
mg milligram (milligramme)
g gram (gramme)
kg kilogram (kilogramme)
mt metric ton (1 000 kg) [also written as tonne]
oz ounce
lb pound
cwt hundredweight [value differs in UK (‘Imperial’) and US units - see weight conversions]
t ton [value differs in UK (‘Imperial’) and US units - see weight conversions] psi pounds per square inch
GPM (‘Imperial’ = UK) gallons per minute
MGD million (‘Imperial’ = UK) gallons per day
CFM cubic feet per minute
ppt parts per thousand (‰)
ppm parts per million
ppb parts per billion (thousand million)
min minute
hr hour
kWhr kilowatt-hour

Conversions
THIS SECTION OF THE ANNEX should be used in conjunction with the abbreviations sec tion. Please note that the words gallon and ton have different values depending on whether the source of the text you are reading is ‘British’ or ‘American’ in origin.
LENGTH:
1 µm 0.001 mm = 0.000001 m
1 mm 0.001 m = 1 000 µm = 0.0394 inch
1 cm 0.01 m = 10 mm = 0.394 inch
1 m 1 000 000 µm = 1 000 mm = 100 cm = 0.001 km = 39.4 inch = 3.28 ft = 1.093 yd 1 km 1 000 m = 1 093 yd= 0.621 mi
1 inch 25.38 mm = 2.54 cm
1 ft 12 inch = 0.305 m
1 yd 3 ft = 0.914 m
1 mi 1 760 yd = 1.609 km
WEIGHT:
1 µg 0.001 mg = 0.000001 g
1 mg 0.001 g = 1 000 µg
1 g 1 000 000 µg = 1 000 mg = 0.001 kg = 0.0353 oz
1 kg 1 000 g = 2.205 lb
1 mt 1 000 kg = 1 000 000 g = 0.9842 UK t = 1.102 US t
1 oz 28.349 g
1 lb 16 oz = 453.59 g
1 UK cwt 112 lb = 50.80 kg
1 US cwt 100 lb = 45.36 kg
1 UK t 20 UK cwt = 2 240 lb
1 US t 20 US cwt = 2 000 lb
1 UK t 1.016 mt = 1.12 US t
VOLUME:
1 µl 0.001 ml = 0.000001 L
1 ml 0.001 L = 1 000 µl = 1 cc
1 L 1 000 000 µl = 1 000 ml = 0.220 UK gallon = 0.264 US gallon
1 m3 1 000 L = 35.315 ft3 = 1.308 yd3 = 219.97 UK gallons = 264.16 US gallons 1 ft3 0.02832 m3 = 6.229 UK gallons = 28.316 L
1 UK gallon 4.546 L = 1.2009 US gallons
1 US gallon 3.785 L = 0.833 UK gallon
1 MGD 694.44 GPM = 3.157 m3/min = 3 157 L/min

CONCENTRATION - DISSOLVING SOLIDS IN LIQUIDS:
1 % 1 g in 100 ml
1 ppt 1 g in 1 000 ml = 1 g in 1 L = 1 g/L = 0.1%
1 ppm 1 g in 1 000 000 ml = 1 g in 1 000 L = 1 mg/L = 1 µg/g
1 ppb 1 g in 1 000 000 000 ml = 1 g in 1 000 000 L = 0.001 ppm = 0.001 mg/L
CONCENTRATION - DILUTION OF LIQUIDS IN LIQUIDS: 1 % 1 ml in 100 ml
1 ppt 1 ml in 1 000 ml = 1 ml in 1 L = 1 ml/L = 0.1%
1 ppm 1 ml in 1 000 000 ml = 1 ml in 1 000 L = 1 µl/L
1 ppb 1 ml in 1 000 000 000 ml = 1 ml in 1 000 000 L = 0.001 ppm = 0.001 ml/L
AREA:
1 m2 10.764 ft2 = 1.196 yd2
1 ha 10 000 m2 = 100 ares = 2.471 acres
1 km2 100 ha = 0.386 mi2
1 ft2 0.0929 m2
1 yd2 9 ft2 = 0.836 m2
1 acre 4 840 yd2 = 0.405 ha
1 mi2 640 acres = 2.59 km2
TEMPERATURE:
°F (9 ? 5 x °C) + 32
°C (°F - 32) x 5 ? 9
PRESSURE:
1 psi 70.307 g/cm2
Scientific units

Scientists have a different way of writing some of the units described in this glossary. They use what is called the Systeme International (SI). The units are referred to as SI units. For example: 1 ppt, which can be written as 1 g/L (see concentration above) is written as 1 g L-1 in scientific journals. 1 g/kg is written as 1 g kg-1. 12 mg/kg would be written as 12 mg kg-1. 95 µg/kg would be written as 95 µg kg-1. A stocking density of 11 kg/m3 would be written as 11 kg m-3. This system of standardisation is not normally used in commercial aquaculture hatcheries and grow-out units and has therefore not been used in this manual. More infor mation about this topic can be found on the internet by searching for SI Units (e.g. www.ashree.org/book/siguide.htm)